Spinneret assembly



1957 R. H. BAUNLICH'ET AL 2,803,851

SPINNERET ASSEMBLY Filed March 1:5, 195s United States Patent Ofiice 2,803,85l Patented Aug. 27, 1957 SPINNERET ASSEMBLY Richard H. Braunlich, West Chester, Harry N. Ghenn, Media, Robert C. Messmer, Chester, and Ray A. Randolph, Drexel Hill, Pa., assignors to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Application March 13, 1953, Serial No. 342,254

25 Claims. (Cl. 18-8) This invention relates to apparatus for spinning a liquid from which textile fibers, for example, viscose rayon are formed. More particularly, the invention has to do with an improved construction of the spinneret in such a spinning machine.

We have found several disadvantages in the conventional operation of a spinning machine and particularly when spinning thick-thin yarn in accordance with the teaching of Richard H. Braunlichs copending application Serial No. 292,929. For example, an important requirement for satisfactory spinning is to eliminate all air pockets and entrapped bubbles in the spinneret assembly. This is ordinarily done by flushing the spinneret when it is turned to a substantially vertical position. However, due to the well-known shape and construction of the candle filter and rounder, it is impossible to point the spinneret upwards except when it is over the spinning bath. To flush the spinneret in this position entails the deposit or liquid viscose in the spinning bath which coagulates and clogs the spinning machine apparatus and seriously impedes the satisfactory winding and collecting of one or more of the various ends. It is also desirable to provide in the spinneret a construction which reduces or eliminates areas of stagnant viscose and which will not leak around the coupling at any point between the spinneret and the rounder.

A primary object of the invention, therefore, is to provide a spinneret assembly capable of being flushed in any position to eliminate air bubbles.

A further object of the invention is to provide a spinneret assembly having a minimum free volume for the liquid passing theerthrough.

A further object of the invention is to provide a contoured liquid bore for a spinneret assembly which eliminates non-flow or stagnant areas.

A further object of the invention is to provide a special insert for a spinneret having good insulation between the spinning bath and the liquid flowing through the spinneret. A further object is to design a spinneret eliminating the pockets as well as areas of low fluid flow velocity.

A further object of the invention is to provide a spinneret connection having adequate seals to avoid all leaking of the liquid.

A further object of the invention is to provide an insert for a spinneret of a material to which air bubbles have little tendency to cling.

A further object of the invention is to provide a relatively incompressible insert for a spinneret to maintain constant volume of liquid in the spinneret.

A still further object is to provide an improved spinneret assembly construction which greatly facilitates cleaning prior to connecting the spinneret to the rounder.

Further objects will be apparent from the specification and drawings in which; t

Figure 1 is a view showingthe manner in which a spinneret is installed on a spinning machine and also illustrating a procedure used to rid the spinneret of air pockets or bubbles; l

, viscose through the spinneret 10.

Figure 2 is an enlarged transverse sectional detail of our improved spinneret construction attached to the rounder;

Figures 3 and 4 illustrate the novel portions of Figure 2 in a slightly modified form; and

Figure 5 shows a further modification having a somewhat difierent type of seal.

The invention comprises essentially the provision of a specially designed insert and cap which are clamped between the spinneret proper and the glass rounder. This insert is desirably fabricated of polytetrafiuoroethylene, a product sold on the market under the name Teflon, and is so constructed that a filter is securely clamped between the insert and the cap without any leakage. The spinneret assembly construction in accordance with the present invention can be readily cleaned without destroying the efficacy of the leakproof construction and particularly without the necessity for disassembling the insert and cap. For purposes of definition, the term inert is used herein to refer to the member which is physically placed within the spinneret and the term cap is used to refer to the cooperating member which is detachably' sealed to the insert. In the embodiment described herein, the insert proper extends beyond the base of the spinneret and the insert together with the cap in efiect form a two-piece element which is inserted between the spinneret and the glass rounder. It is immaterial whether the insert is considered to be entirely within the spinneret or a member which extends into the spinneret and. separates and seals the spinneret with respect to the rounder.

Referring now more particularly to the drawings, a spinneret assembly 10 is shown in Figure 1 connected to a conventional glass rounder 11 which is submerged in a suitable spinning bath 12. The liquid from which textile fibers are formed is extruded through the spinneret into the bath to form a plurality of fine filaments 13 which are collected, washed, and spun into a cake in accordance with well-known practice. The rounder 11 is attached to a candle filter 14 pivoted at 15 to a bracket 16 clamped to the main liquid supply line 17. A pump 18 provides the necessary pressure for extruding the liquid such as In order to completely flush air from the spinneret assembly, it has heretofore been necessary either to swing the candle filter and the attached rounder and spinneret to dotted line position shown at A in Figure 1 or to swing just the rounder and spinneret to a vertical position over bath 12. Since it is essential to remove all traces of air before the machine is laced-up, the flushing position shown at A is unsatisfactory because the spinneret assembly is not aimed in a vertical direction and therefore all air is not positively removed. Also, viscose flushed from the spinneret in this position is likely to spill onto the Working mechanism of the spinning machine such as the pump, gears, etc. On the other hand, if the spinneret assembly is flushed simply by turning the rounder to the position shown at B in Figure 1, then the entrapped air can be satisfactorily re moved because the spinneret is pointing substantially upwardly but this operation causes viscose to be deposited in the bath 12 with the result that coagulated particles'of viscose hinder satisfactory lacing-up and sometimes adhere to the filaments 13 as well as to other parts of the spinning machine. This is a highly unsatisfactory condition.

Our improved construction which achieves the various objects enumerated above, comprises a special cylindrical insert 20 and a cooperating cap 21 both formed of a material such as Teflon. The insert 2% and cap 21 are clamped against the rounder flange 22 by means of the standard rounder nut 23 and split coupling 24. The spinneret proper 25 is of conventional construction comprising a metallic cup having a plurality of orifices in its face 25a and an annular turned flange 25!) by means of a reduced bore 27 which flares outwardly towardsthe:

perforated face 25a of the spinneret. To avoidcreati'on of stagnant areas, we have found that it is desirable-that the angle between the'flared portiont27a of theboreand the face 25a be not less than 45 and preferably maybe as much as 60 as shown in Figure 2. The opposite end of bore. 27 curves outwardly to form a, hollow recess 27b: in the insert 20 having generally hemispherical sides. The filter 26 is clamped between the insert 20 and the: cap: 21 through pressure exertedbetween the; annular flange 23a; of nut 23 and the rounder flanger22, Theb'ore 21a of cap 21 diverges from a diameter equal to the: bore: 11a

of rounder 11 to a diameter; substantially-equal toathe maximum diameter of recess 27b. The sides of 'bore'21a';

however, are more. nearly conical throughout their: mid portion and, therefore, appear, as straight. linesin the sectional showingof Figure 2. A-small radius is pro= videdat-each terminus of the bore 21a and the angle. between the conical sides and a plane substantially parallel tothefaceZSa is desirably notless than 36 andprefer ablyshould'bein the range of 45 to 60.

In order-.toprovide adequatensealing' with a minimum. of pressure'requiredto be exerted between the nut 23. and coupling 24; we provide'a sliding'fit between .the insert 20 and the spinneret 25.. The outermost annular edge 20a of the insert is, however, pressed tightly against the inside of the spinneret toprovide a tight seal at this point. The base: of insert 20 has .an annular shoulder 28!) (Figure 3) which. has a slightly convex face 200 dimensioned to have a tight sealing fitin the enclosing. flange 21b of cap 21. Face 200 of shoulder'lflb' may be. either arcuateor-formed of sections of oppositely pitched truncated cones. The insert 20 shownin. Figure 3 is identical to the insert shown in Figure. 2 but in an un-. stressed conditionto illustrate the snap action sealzdue to theconstruction of shoulder 20b. Thecooperating socket formed in cap 21 shown in Figure 4 has an-inwardly flared or undercut inner walli21cwhich cooperates with the shape of shoulder 20b to provide the satisfactory sealing fit. The diameter of thecface of shoulder 29b. is slightly less than the diameter-of the socket or wall 216 so that assembly is facilitated: The maximum. diam-. eter of. shoulder 21H) or face 200, however, is-somewhat greater than this diameter and cooperates with the-taper in socket 210 tov securelylock the cap and the insert to-.- gether. In this regard, the cap-of Figure 4 isv identical to the cap shown in Figure 2 but the Figure 4 illustration illustratesa somewhat modified contour. for-theibore as will bemore clearly described hereinafter.-

It is to be no-tedthat we provide-substantial clearance at 28 bet-ween the inner shoulder of flangeZtlb' and. the outside of spinneret flange 25b. Full sealing between the cap 21 and the rounder ll is provided at 29 at the point where the radially inward area of the convex face or base ofcap 21 contacts theouter face of rounder flange 22.. The-wall thickness of the cap base at 29 issuchuthat moderate compression of the cap maytake place -in-this area to insure sealing,but it is important that the annular bead 30 on the rounder flange 22 has suflicient clearance at 31 so that there is nocontact betweenithebeadxand the cap even when nut 23 isdrawn up tightly; It has been found impractical to eliminatesthe beadStlflon the rounder because, without the additional. reinforcing-supplied by the head, the rounder flange 22 was subject to constant breakage. An annular relief groove 32 may be provided around the body ofthe insert 2010- facilitate assembly and disassembly of the insert '20'and the spinneret 25. It is also noted that. there is atapered gap or relief area provided around. the. outer periphery ofv the cap .face sothat. compressive force. is concentrated: at 29..

A particular advantage of this construction is to decrease the compressive force which may be applied between coupling 24 and nut 23 so that there is no danger of bending or deforming the flange 25b. If found desirable, the cooperating faces of the cap and the insert can also be made slightly convex for the same reason. It will thus be evident that all axial sealing pressure is applied at the extreme outer termini of the spinneret assembly, viz.,

insert edge20'a and cap base 29. The seals at 20'a-and around theperipheryof the enlarged bore 21a or-35-inz the: cap 'i'sie'liminated.

Theinsert 36 shown inFigure .5 has a bore 37 'which.

flares at 37a at an angle of substantially 45 with regard to the face 25a of the spinneret 25. It has been found t'hatthisangle. should not be smaller if stagnant areas are to becompletely avoided. Theslightly modified cap 38 hasa bore 38a having substantially conical sides at an anglenof. approximately 45 Thev radii of the termini oflth'e. boreare somewhat smallerthan those shown in Figure 2 to. a1l'ow for the smalleraxial dimension of the cap andfthesomewhat fiattericonvex base. The insert 36 has'a sliding fitaround itsperiphery in the spinneret-25 and-both axialuand radial sealing are provided at 36a. RadialIseal-ing at the base of the insert, however, is by means of 'a-: rubberO-ring39 which is compressed between the somewhat thinner flange 38b ofcap 38 and an annular seat 36b.,at the base of insert 36. in the formof Figure 5, axial sealing of theassembled spinneret is present at 36a, 40 'and 29.- Radial sealing is provided at 36a, 41 iand42 aswell as at.29 so that there can be no leakage of liquidfwh'en the spinneret assembly is in operation.

The use of"polytetrafluoroethylene provides two especially desirable and unexpectedfeatures in spinneretconstruction of the present type. First, this material is of such a. greasytnaturethat bubbles of air do not readily cling to. the borenofthe insert or the cap. This phenomenon is far more noticeable :than when other materials such as rubberare used. Second, polytetrafluoroethylene is lesscompressible-thanrubber.so that whenthe spinneret is used'in conjunction with the above-mentioned thick-thin'process, the, surges. in pressure do not'cause variations'injthe liquid volume of the insert and cap.v Such changes in volume havebeen found to be anextremely undesirable characteristic of a rubber insert. Al though polytetrafluoroethylene has been found tobe most satisfactory for the above-mentioned reasons, other synthetic plasti'c materials" giving better results than rubber can be used to advantage. Examples of such are polystyrene "and polyethylene, the latter of which is morecompressible than" polytetrafluoroethylene but substantially cheaper.

Another advantage of thepresent construction'is found in the secure retention vof thefilter 26 due to the clearance provided 'at 28'and the concentration of compressive for-cearound the filteradjacent the major diameter of' bores 2121; 27b'and'38a, 35 because'of the convex. shape of the cap face .at29.' This construction .of the cap face and the provision of the shapedbores 21a, 27b, 35 and 38deeliminate the. air pocket'customarily present between therubber gasket and the glassrounder flange 22.

It will thus be understood that we have provided an improved spinneret assembly which automatically; pre vents tor inhibits'the "formation: of'air pocketsand stagnant.=.areas.;x It; alsoeinsures the removal: of .such' air. pockets or;bubbles-tawhens'the spinneret is flushed in: any P sition..

lt e iminates the need for any gasketatdha asoasur spinneret flange. It eliminates the need'for any seal at the flange assembly. It reduces the liquid volume in the spinneret to a minimum. It provides for the ready removal of foreign matter such as lint or dust from the spinneret side of the filter and the bore of the insert. This operation is readily accomplished by applying vacuum to the assembled insert, filter and cap before installation of the spinneret proper. The present construction also insulates the unextruded liquid from the relatively high temperature spinning bath, thereby inhibiting premature coagulation inside the spinneret.

Having thus described our invention, we claim:

1. In spinning apparatus, the combination which comprises a cup-shaped spinneret, an annular flange surrounding the base of said spinneret, a rounder, an annular flange at one end of said rounder, an insert for the spinneret, said insert having a base, walls defining a first relatively small diameter bore near the mid-portion of said insert and extending axially thereof, walls defining a flared continuation of said bore diverging towards the face of the spinneret, walls defining a flared continuation of said bore adjacent the base of the insert, a cap positioned adjacent the base of the insert and beyond the flange of the spinneret said cap being in liquid-tight seal; ing engagement with the base of the insert, walls defining an enlarged bore in said cap face-to-face with the flared bore at said insert base, a convex annular sealing face on the cap in contact with the rounder flange, and means for clamping the insert and cap between the spinneret and the rounder flange.

2. Spinning apparatus in accordance with claim 1 in which the insert is made of polytetrafluoroethylene.

3. Spinning apparatus in accordance with claim 1 in which both the insert and the cap are made of polytetrafluoroethylene.

4. Spinning apparatus in accordance with claim 1 in which both the cap and the insert are made of a synthetic plastic material.

5. Spinning apparatus in accordance with claim 1 in which the angle between the first mentioned flared bore of the insert and the face of the spinneret is not less than 45 6. Spinning apparatus in accordance with claim 1 in which the angle between the first mentioned flared bore of the insert and the face of the spinneret is between 45 and 60.

7. Spinning apparatus in accordance with claim 1 in which the second mentioned flared bore in the cap is substantially conical, with its walls making an angle with a plane substantially parallel to the face of the spinneret of not less than 36.

8. Spinning apparatus in accordance with claim 1 in which the second mentioned flared bore in the cap is substantially conical, with its walls making an angle with a plane substantially parallel to the face of the spinneret within the range of 36 to 45.

9. Spinning apparatus in accordance with claim 1 in which the seal between the cap and the base of the insert comprises an O-ring.

10. In spinning apparatus, the combination which cornprises a cup-shaped spinneret having a perforated face, an annular flange surrounding the base of said spinneret, a rounder, an annular flange at one end of said rounder, an insert substantially filling the spinneret and pressure sealed against the inside of said face, said insert having a base, walls defining a first relatively small diameter bore near the mid-portion of said insert and extending axially thereof, walls defining a flared continuation of said bore diverging towards said spinneret face, walls defining a diverging hemispherical continuation of said bore adjacent the base of the insert, -a cap positioned adjacent the base of the insert and beyond the flange of the spinneret and having a pressure seal with the base of the insert, walls defining an enlarged bore in said cap faceto-face with the flared bore at said insert base, a convex annular sealing face on the cap pressure sealed against the rounder flange, and means for clamping the insert and the cap between the spinneret and the rounder flange.

11. Spinning apparatus in accordance with claim 10 in which both the cap and the insert are made of a synthetic plastic material.

l2. Spinning apparatus in accordance with claim 10 in which the angle between the first mentioned flared bore of the insert and the face of the spinneret is between 45 and 60.

13. Spinning apparatus in accordance with claim 10 in which the second mentioned flared bore in the cap is substantially conical, with its walls making an angle with a plane substantially parallel to the face of the spinneret of not less than 36.

14. Spinning apparatus in accordance with claim 10 in which the second mentioned flared bore in the cap is substantially conical with its walls making an angle with a plane substantially parallel to the face of the spinneret within the range of 36 (to 45 15. Spinning apparatus in accordance with claim 10 in which the seal between the cap and the base of the insert comprises an O-ring.

16. A spinneret assembly comprising a cup-shaped spinneret having an annular flange around the base of the spinneret and a perforated face opposite said flange, a substantially cylindrical insert in said spinneret and having a free sliding fit between the periphery of the insert and the inside of the spinneret, a relatively narrow annular sealing face on the insert in pressure sealing contact with the face of the spinneret, an enlarged shoulder at the opposite end of the insert, said shoulder extending radially beyond the bore of the spinneret and in axial spaced relation to the flange on the spinneret, walls defining a restricted bore in the insert, Walls defining a diverging flare connecting the bore and the sealing face, walls defining a diverging bore at the opposite end of the insert and providing communication with the relatively narrow bore and an annular relief groove around the periphery of the insert to facilitate sliding contact between the insert and the spinneret.

17. An insert in accordance with claim 16 in which the periphery of the flange is outwardly convex.

18. Apparatus in accordance with claim 16 having a cap positioned over the flange on the insert. and in liquidtight sealing contact therewith.

19. Apparatus in accordance with claim 18 in which the cap is provided with a recess for receiving the flange, the walls of said recess converging outwardly to provide a tight snap fit between the cap and the insert.

20. Apparatus in accordance with claim 18 in which a resilient O-ring is compressed between the cap and the insert to provide a liquid-tight seal.

21. Apparatus in accordance with claim 18 in which the cap has an outwardly convex sealing face on the opposite side of the insert.

22. Apparatus in accordance with claim 18 in which both the cap and the insert are made of a synthetic plastic material.

23. Apparatus in accordance with claim 18 in which both the cap and the insert are made of polytetrafluoroethylene.

24. Apparatus in accordance with claim 18 in which the cap has walls defining a substantially conical bore in line with and face-to-face with the diverging bore remote from the spinneret face.

25. In spinning apparatus, a spinneret assembly comprising a spinneret, a polytetrafluoroethylene insert slidably positioned in said spinneret and having a bore extending from end-to-end therethrough, walls defining a diverging terminal portion at one end of said bore, walls defining a reduced diameter portion of said bore in alignment with said diverging terminal portion, walls defining an opposite terminal hemispherically shaped portion of 7 8 saidhbre; aflpolytetrafliloroettfylene cap -positidned adja the'"cap; and* liquid-sealing m'ea'ns between the cap" ahd= cent thefinnefen'd-of 'theinsert; a filter bet-ween tfie'cap'= the insert! and the insert, walls defining an-enlrged hemispli'e'risal bore in tlfecap in registrywi'ttithehemipfierical' terminal ReferellcEyCi'ied iflthefileof thislpate'nt bore portien of 'tfie' ihsert', said kemiph'eri'alfiore por- UN TE A E P E S tions in-thecap and the insert being separatedby the e v filter, a convex pressure-sealing surfaceon'the backof 20785O9 Hutton 1937 

